Luminous tube using rarefied gases



Dec. 28, 1926. 1,612,340

J. B. J. M. ABADIE LUMINOUS TUBE USING RAREFIEi) GASES Filed Feb. 18. 1925 big Patented Dec. 28, 1926.

I UNITED STATES PATENT OFFICE.

JEAN-BAPTISTE JOSEPH MARCEL ABADIE, 0F PARIS, FRANCE, ASSIGNOR. BY MESNE ASSIGNMENTS, TO RAINBOW LIGHT INC., OF NEW YORK, N. 'Y., A CORPORATION OF NEW YORK.

LUMINOUS TUBE USING RAREFIED GASES.

Application filed February 18, 1925, Serial No. 10,151, and in France Iarch 24,1924.

The present invention relates to improvements in luminous tubes in which the atmosphere is rarefied. The object thereof is to maintain in these tubes the. desired constant pressure of the conducting gas, and this result is obtained by enclosing within the tube substances which release increments of the conducting atmosphere automatically as required to maintain substantially uniform conditions of conductivity therein.

Preferably this automatic control is effected by variations in the temperature of the electrodes, or parts thereof as will be.

hereafter described, by reason of which upon the depletion of the conducting atmosphere dissociation or change in vapor tension of the gas or vapor producing substances will take place so as to replenish the atmosphere to the extent desired and thus preserve its conducting properties.

The invention also relates to an improved luminous tube in which the method of automatic regeneration of the conducting atmosphere will be carried out in its operation. One form of such a tube is illustrated in the atfzcompanying drawing forming a part here- 0 By means of the present invention I obtain luminous tubes having a rarefied atmosphere and of different colors by utilizing the luminous spectra of different substances. \Vith this end in view the invention utilizes (for the purpose of creating the atmosphere necessitated by the desired color and to maintain the atmosphere under a constant desired pressure) the phenomenon of dissociation of various salts or the change in vapor tension of various substances.

The salts which are preferably used to supply vapor or gas to the conducting atmosphere as it is depleted are those which are dissociated or Whose vapor tension is changed at temperatures ranging from an approximate maximum of 400 downward to such minimum temperatures as would be met with in the electrodes of a practical luminous tube. The salts comprised in this category (examples of which will be presently referred to) are numerous and interesting, both because of the colors that can be obtained by their use, as well as the constancy of pressure and of working conditions which (rm be maintained in the vacuum tube automatically as will be described.

In carrying my invention into efiect it Wlll be understood that the vacuum tube is of the usual t pe in which interior electrodes are employed. The tube contains a conducting gas or vapor which becomes luminous upon the passage of a high tension discharge between the electrodes. As is well known with such tubes the pressure of the conducting atmosphere at which the greatest luminosity is secured does not strictly coincide with the pressure which provides maximum conductivity. When such a tube is operated, the gas or vapor constituting the conducting atmosphere gradually becomes depleted, resulting in a reduction in pressure and eventually the resistance becomes sohigh as to make it impossible for the discharge to pass through it. As the pressure diminishes there is first a rise in the current, followed by a dropping off of the current rapidly to zero. As the pressure in the tube falls from that required to give maximum luminosity the succeeding current rise results in an increase in the area of cathode bombardment as evidenced by the so-called negative glow and this phenomenon I utilize for the purpose of automatically. volatilizing or changing the vapor tension of the salts or substances which are depended upon to regenerate the conducting atmosphere.

Th1s increase in area of the cathode bombardment is accompanied by a rise in temperature of that portion of the electrode which was not formerly coincident therewith. When the increase in area of the cathode bombardment is suflicient to involve the entire electrode, the cathode fall in potential which increases with a further increase of current through the tube will be accompanied by a very considerable increase in temperature of the electrode.

In order to utilize this increase in temperature the electrode is made hollow or-is provided with a hollow portion of suitable dimensions, these dimensions being Variable, according to the nature of the salt which dissociates and according to the character of the current under whlch it is desired to cause the vacuum tube to operate.

By way of example, there is shown in the drawing a hollow electrode 4 having a forward extreme end 5, in the form of a closed cone, and the body 6 of the electrode consists of a metal gauze-cylinder containing the salt to be dissociated. In the operation of such an electrode its area is so chosen 1 of gas from the material contained in the perforated body of the electrode. example, under these normal conditions the electrode is normally functioning so that conductivity therefr m will be confined only to the closed conical end' 5, then upon an increase of current due to a reduction of pressure, the area of the cathode bombardment as evidenced by the negative glow will be increased so as to extend more or less over the perforated body of the electrode, thereby heating the same and causing the substances therein to be dissociated or vaporized.

If however the normal operation of the tube involves the functioning of the entire surface of the electrode including the perforated body thereof, then an increased current due to a reduction in pressure will be accompanied'by a rise in temperature of the electrode as to result in the evolution of gas or vapor from the contained material. In the latter case, care of course should be taken that the temperature of the electrode under conditions of normal pressure is below the point at which the materials become dissociated or have their vapor tension changed.

hen a charge of the gas or vapor has thus been evolved to replenish or regenerate the conducting atmosphere, the pressure will rise, accompanied by a fall of current and a restoration of conditions to normal.

By way merely of examples of salts which may be used, I may employ nitrates of so dium, lithium, strontium, thallium and other alkaline metals. The electrodes may be made of carbon and by employing suitable salts therein such as nitrite of-sodium or acid carbonate of caesium I have been able to obtain a tube giving a white light closely approximating day-light.

Having now described my invention, what I claim as new therein and desire to secure by Letters Patent is as follows:

1. A luminous tube containing a rarefied conducting atmosphere and having electrodes therein, one of said electrodes carrying the salt or substance from which the conducting atmosphere is restored when depleted, whereby a reduction in pressure within the tube will be accompanied by a rise of current therein to cause said substance to be dissociated or changed in vapor tension If, for I and the pressure of the conducting atmosphere will. bemaintained substantially uniform, substantially as set forth.

2. A luminous tube containing a rarefied atmosphere at a pressure greater than the pressure corresponding to the maximum of electrical conductivity in the tube and mterior electrodes, one of which carries a salt adapted to be dissociated in the operation of the tube upon a drop in pressure of the atmosphere therein, whereby the pressure of said atmosphere will be automatically maintained substantially constant, substantially as set forth.

The method of maintaining the atmosphere of a luminous tube at a substantially constant pressure which consists in causing an increase of current due to a fall in pressure to dissociate a chemical salt within the tube and evolves gas therefrom, thus restoring the pressure to normal, substantially as set forth.

4. A luminous tube containing a rarefied the tube body adapted to give off rarefied electrodes therein and a substance within atmosphere and comprising a tube body with gases under the effect of an increase in area of cathode bombardment resulting from an increase of current corresponding to the fall in pressure, substantially as set forth.

5. A luminous tube containing a rarefied atmosphere and comprising a tube body and electrodes within said tube body, one of said electrodes having an apertured portion containing a substance adapted to give off rarefied gases under the effect of a change in the area of cathode bombardment due to variations in current resulting from pressure variation within the tube, substantially as set forth.

6. A luminous tube containing a rarefied atmosphere comprising a tube body and electrode within said. tube body, one of said electrodes having an apertured portion within the tube terminating in a hollow end and a substance adapted to give off rarefied gases placed in said apertured portion, substantially as set forth.

7. A luminous tube containing a rarefied atmosphere and interior electrodes, of which electrodes a main discharge electrode carries a salt adapted to be dissociated in the operation of the .tube upon a drop in pressure of the atmosphere therein, whereby the pressure of said atmosphere will he automatically maintained substantially constant, substantially as set forth.

JEAN-BAPTISTE JOSEPH MARCEL ABADlE. 

